Adjustable boring head for earth augers



April 28, 1970 J BENETT| ET AL 3,508,622

ADJUSTABLE BORING HEAD FOR EARTH AUGERS Filed May 13, 1968 3 Sheets-Sheet 1 as s7 s4 23 2 11 IN V EN TOR.

JOHN G. BENETTI By WALTER L. STURGEON ATTORNEY Iii April 28, 1970 BENETT| ET AL 3,508,622

ADJUSTABLE BORING HEAD FOR EARTH AUGERS Filed May 13, 1968 3 Sheets-Sheet 2 IN VEN TOR.

JOHN G. BENETTI BY WALTER L.STURGEON ATTO RNEY April 28, 1970 BENETT] ET AL 3,508,622

ADJUSTABLE BORING HEAD FOR EARTH AUGERS Filed May 13, 1968 3 Sheets-Sheet 5 IN V EN TOR. JOHN G. BENETTI By WALTER L.STURGEON ATTORNEY United States Patent US. Cl. 175-292 14 Claims ABSTRACT OF THE DISCLOSURE An adjustable boring head for earth augers, particularly adapted for horizontal boring, has a hub with radial arms. An extension fits on each arm is telescopic fashion so that it can be held in various positions, thus determining the diameter. The arms and extensions have holes to receive bolts which also pass through individual clamps which cooperate to retain teeth in position. Bevelled washers or bevelled bosses as cast integrally on the extension govern the angle of the direction of the tooth relative to the bolt axis. An expansion holder is pivotally mounted on the top of at least one extension and is shaped so that when the auger is rotated in digging direction the expansion holder pivots outward so that the tooth held thereby digs the outside of the hole and when the auger is reversed pivots inwardly to reduce the overall diameter of the head. The same clamp and tooth are used on the expansion holder as on the extension. A hub attachment fits into the hub and holds an elongated pilot gimlet which assists in holding the direction of the hole true. The hub attachment also holds a pair of teeth.

This invention relates to a new and improved adjustable boring head for earth angers.

One of the features of the invention is the fact that there is provided a hub to which the auger shaft and the pilot bit are attached and from which project at least two substantially radial arms. Each arm may carry an extension and the arm and extension are formed in such manner that they interfit so that the extension slides radially relative to the hub without rotation relative thereo. The extension and the arm are provided with a plurality of holes to receive bolts which fix the diameter of the head. The aforementioned bolts may be the same bolts which attach the removable teeth to the auger head as hereinafter explained. A principal feature of the invention is the fact that the diameter of the head may be adjusted to accommodate different hole diameters while using a single hub and arms. It will further be understood that the extensions may be interchanged for those of greater length, thereby further improving the versatility of the device for different hole diameters.

Another feature of the invention is the fact that a separate clamp member is used for each tooth. The tooth is positioned between the arm or extension and the clamp and a bolt fit through the aforementioned parts and when drawn tight by a nut on the underside of the head the tooth is locked in position. In a preferred form of tooth, the tooth is slotted by means of a slot extending forwardly from the proximal end of the tooth. The tooth may conveniently be removed for sharpening or replaced when worn. By changing the size of the clamp, different size teeth can be used.

Another feature of the invention is the provision of a bevelled washer which fits between the underside of the tooth and the arm or extension and is rotatable about the axis of the bolt thereby adjusting the angle which the tooth assumes relative to the bolt and hence relative to the auger head. It will be understood that there are several teeth spaced along the arm or extension which overlap so that the cutting edges of the teeth encompass the entire area of the hole being dug in an overlapping fashlOIl. To facilitate such result, it is desirable that different teeth be disposed at different angles depending upon the distance from the axis of rotation of the auger head and this is readily accomplished by means of the bevelled washer which has been described.

Alternatively, instead of a bevelled washer being used, the extension may be cast in such manner that the equivalent of bevelled washer is integral with the surface of the extension and thus bosses are formed on the extension surface against which the teeth are drawn snug and the angles of said bosses accomplish the same results as the bevelled washers which have been described.

Another feature of the invention is the fact that the bolt which holds the clamp in place becomes a part of the clamp and absorbs much of the abrasion of the digging action which would otherwise be absorbed by the clamp. Since it is relatively inexpensive to replace the bolts when worn, the clamps are protected against excessive wear.

Another important feature of the invention is the fact that an expansion tooth holder is pivotally mounted adjacent the top of the outer end of at least one extension. A tooth is held by the extension disposed in a different plane from the teeth which have been described and which are attached to the extension itself. When the auger is rotated in a digging direction, the shape of the extension holder is such that the tooth is projetced outwardly beyond the confines of the auger head and thus the hole dug is of a diameter greater than that of the auger head. When the direction of rotation of the auger is reversed, the expansion holder is pivoted into inoperative or retracted position so that the overall diameter is limited to the diameter of the extension. This feature is of particular importance in horizontal boring where it is frequently desired to advance a casing having an internal diameter about equal to the diameter of the boring head as the hole is being dug. The expansion tooth provides clearance which enables the casing to be forced forwardly but at the same time the retraction of the expansion tooth permits the boring head to be retracted within the casing when the auger is to be withdrawn.

Another feature of the invention is the fact that the clamp which holds the expansion tooth in place is the same in configuration as the clamp which holds the teeth on the extension.

Another feature of the invention is the provision of an adjustable means which limits the maximum protrusion of the expansion tooth and which can be adjusted depending upon the conditions of the job being performed.

Still another feature of the invention is the provision of means for ready attachment of a single flight auger to the boring head. It will be understood that if different diameter holes are to be dug by the adjustable head, the auger flight diameter must correspond to the hole being dug and this requires that the head be interchanged with different flight sizes. An apertured lug is formed on the lower end of the flight and is fastened by a bolt to a hole provided in the extension corresponding in position to the hole on the opposite side of the head which receives the expansion tooth holder.

Still another feature of the invention is the provision of a central hub formed to receive different size boring arms and convenient means for attaching said arms to the hub.

Another feature of the invention is the provision of a noncircular socket in the boring head which receives a complementary extension of a gimlet-shaped pilot for the auger. The gimlet may be attached to the auger head conleniently by means of a single bolt which may also be ised to attach the auger shaft to the head.

Another feature of the invention is the provision of neans for holding at least two teeth on the extension of the Jiolt gimlet which teeth are disposed to dig into the bottom )f the hole being dug in very close proximity to the hole Formed by the gimlet. It will be understood that disposing :eeth in such position and at such angles as to traverse :he portion of the hole being dug closest to the hole left Jy the pilot is a principal design problem in auger head :onstruction and the present invention facilitates solution )f such problem.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings.

In the drawings:

FIG. 1 is a side elevational view partly broken away in section of an auger head and pilot bit in accordance with be present invention.

FIG. 2 is a perspective view partly broken away to reveal internal construction of a portion of the structure of FIG. 1.

FIG. 3 is a transverse sectional view taken substantially along line 3-3 of FIG. 1.

FIG. 4 is a sectional view taken substantially along the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary top plan view in enlarged scale of a portion of the structure of FIG. 1.

FIG. 6 is a side elevational View of the structure of FIG. 5.

FIG. 7 is a perspective view of a portion of the structure of FIG. 1 with parts removed to reveal details of construction.

FIG. 8 is a perspective View of a pilot, pilot extension and teeth held thereby.

FIG. 9 is a fragmentary =vertical sectional view taken substantially along the line 9-9 of FIG. 8.

The auger head 11 has a central hub 12 preferably formed with a noncircular bore 13 and having extending therefrom radial horizontal arms 13 here shown as two in number spaced 180 apart. Directing attention to FIG. 3, the top surface 14 of arm 13 is horizontal and on its rearward edge has a depending vertical lip 16. The forward face 17 of arm 13 slants downwardly-forwardly and at its lower end extends horizontally-rearwardly as indicated by reference numeral 18. The angle of face 17 is approximately 45 with respect to the horizontal. The underside of arm 13 below surfaces 14 and 17 slants downwardlyforwardly at an angle of about 30 as indicated by reference numeral 19 for about half of the width of the arm and then slants downwardly-forwardly at a steeper angle of about 70 as indicated by reference numeral 21 until a juncture is made with the underside 18. It will be understood that the cross-sectional shape of arm 13 is subject to variation but the foregoing described has been found to be particularly suitable.

Arranged to slide radially in telescopic fashion relative to arm 13 is an extension 22. Extension 22 has a horizontal top surface 23 from the rearward edge of which depends a lip 24 which lies behind lip 16 in the assembled position of the device. Extension 22 for a considerable portion of its forward face has a downwardly-forwardly inclined surface 26 parallel to surface 17 but near the top of surface 26 is a forwardly projecting abutment 27 At the lower end of surface 26 is a rearward undercurled lip 28 which lies under the surface 18. The underside 29 of surface 26 is parallel thereto and overlies surface 17. It will be observed that the cross-section of the underside of extension 22 is complementary to the upper surface of arm 13. When the extension is slid in from the outer end of the arm 13, the extension is held against unintentional removal. Pluralities of holes 31, 32 are formed in arm 13 and extension 22 to receive bolts 33.. Nuts 34 on the underside of surface 21 draw the bolts tight. The holes 31, 32 are staggered along the lengths of the arm and extension so that the extension may be held in various positions of adjustment which CPI determine the overall radial expanse of the extension and thus determine the diameter of the hole 'bored by the head 11.

A plurality of teeth 36 is held on extension 22 and/or arm 13. Each tooth 36 has a tapered distal portion 37 and its proximal end is bifurccated by means of a slot 38 which extends from top to bottom of the tooth forwardly of the proximal end thereof, the slot 38 being rectangular in top plan and thus providing a pair of prongs 39 on either side therof. The bolt 33 fits through the slot 38. In order to hold tooth 36 in position, a clamp 41 is employed. Clamp 41 has a top surface 42 which is generally slightly downwardly-forwardly inclined and at the forward edge of surface 42 is a downward-forward slanted surface 43 parallel to surface 21. The reaward edge of surface 42 is formed with a heel 44 which fits against the forward edge of abutment 27. The lower surface of abutment 44 has a surface 46 which is parallel and abuts against surface 26. The underside of the clamp 41 has a surface 47 which parallel to surfaces 26, 44 and 29, and the inner edge of surface 47 is determined by a perpendicular surface 48 against which the back end of tooth 36 seats. Hole 49 is formed in clamp 41 in alignment with holes 31 and 32. Thus, bolt 33 fits through hole 49, slot 38, hole 32, and hole 31 and in so doing clamps the tooth 36 in position relative to extension 22. The head 51 of bolt 33 is positioned forwardly and absorbs much of the abrasion of the digging action. Since replacement of bolt 33 is easy and relatively inexpensive, the clamp 41 is protected against excessive wear by head 51. In order to improve the grip of the holder on the tooth 36, a split washer or a rubber-like washer 52 may be positioned in a counterbore in surface 26 to bear against the underside of the tooth 36.

As is best shown in FIGS. 1 and 2, it is desirable that the various teeth 36 be disposed at various angles relative to each other. One means to accomplish this result is to interpose a bevelled washer 53 between the underside of the tooth 36 and the washer 52. The bevelled washer may be rotated about the axis of bolt 33 and depending upon the position of washer 53, the angle which the tooth 36 assumes relative to the axis of the bolt 33 and thus relative to the head is adjusted.

Alternatively, the bevelled washer 53 may be made integral with the extension 22, or in other words he an integral boss on the surface 26, the angle of each boss being different depending upon the distance from the axis of rotation of the auger head.

In conventional practice of horizontal boring for installation of pipes and conduits and the like, it is desirable to advance the boring head and follow up close behind the boring head with a section of the conduit or pipe which is being installed. However, it is desirable that the boring head be retracted back through the pipe or conduit as the work progresses. Accordingly, an expansion feature is desirable in augers used for horizontal boring which is extensible to permit boring of the holes of a diameter slightly greater than the outside diameter of a conduit and then to contract so that the overall width of the head is less than the inside diameter of the conduit. The present invention facilitates such expansion feature. An expansion holder 61 is attached to the outer end of at least one of the extensions 22. Holder 61 has a horizontal portion 62 which pivots about the top surface 23 of eX- tension 22. For such purpose, a vertical hole is formed in portion '62 and hole 60 in extension 22 spaced slightly inwardly from the outer end thereof. A vertical bolt 63 held in place by nut 64 passes through the vertically aligned hole. A substantially vertical flange 66 projects up from horizontal portion 62, being reinforced by a gusset 67. Behind flange 66 is a boss 68 and the flange 66 and boss 68 are apertured for reception of bolt 69 which is held in place by nut 71 behind boss 68. An outward extending abutment 72 is formed on the rearward edge of flange 66. Tooth 36a which is preferably identical with tooth 36 is held flush against the outer surface of flange 66 and is held in position by clamp 41a which is preferably identical with clamp 41. In a preferred form of the invention as best shown in FIG. 6, when viewed in side elevation tooth 36a slants downwardly-forwardly in the direction of rotation of the auger.

Opposite flange 66 on expansion holder 61 is a projection 73 having a surface 74 which is preferably radial relative to the axis of bolt 36. Fixed to the top surface 23 of extension 22 is a block 75 which is threaded to receive an adjustment screw 76 having its axis horizontal and rearward and aligned to engage surface 74.

In the operation of the expansion holder 61, directing attention particularly to FIG. 5, the direction of rotation of the auger head is in a clockwise direction. The holder 61 in its solid line position is shown retracted. As the auger turns, the outer end of tooth 36a contacts the side of the hole being dug and by reason of its digging into the side of the hole, it is swung back about the pivot axis of bolt 63 to the dot and dash line position. When it reaches fully extended position, the surface 74 engages the end of adjustment screw 76 which limits the extent of projection of the end of tooth 36a. Adjustment screw 76 may be turned to cause the point of tooth 36a to extend a greater or lesser distance from the axis of rotation of the head depending upon such variable factors as the thickness of the casing being advanced by the boring head, the extent of wear of the point of tooth 36a and the like. When the head has been advanced for a full stroke of the boring machine or in any event when it is desired to retract the boring head, the auger is turned in reverse direction. Abutment 72 then contacts the side of the hole being dug and the surface 42a of clamp 41a also contacts the side of the hole being dug and this causes the expansion holder 61 to pivot about the axis of bolt 63 from the dot and dash line position of FIG. to the full line position. It is apparent that the overall diameter of the boring head is reduced and this reduction is suflicient to enable the head to be retracted through the casing which has been positioned within the hole being dug.

Inas much as the boring head of the present invention is adjustable in overall width, it is desirable if not essential that the auger have a flight diameter which equals that of the head. As shown in FIGS. 1 and 2, an auger 81 having a single flight 82 helically disposed about a central hollow shaft 83 is provided. The lower edge 84 of flight 82 engages the top surface 23 of the extension 22 on the side of the auger head opposite expansion holder 61. Preferably a rearward extending apertured ear 86 is attached to edge 84. The aperture in ear 86 is aligned with a hole 65 in extension 22 which is positioned identically with the hole receiving bolt 63. Bolt 87 held in place by nut 88 secures lug 86 to extension 22 on the left side as viewed in FIG. 2.

In a preferred form of the invention as best shown in FIGS. 7 and 8, hub 12 is preferably formed with a vertical, hexagonal or other noncircular bore 91. A gimletshaped pilot 92 is provided, it having been found that such a shape helps to prevent the hole being bored from drifting from a straight line. On the upper end of gimlet 72 is a pilot extension 93 complementary to bore 91. In a further preferred form of the invention, intermediate gimlet 92 and extension 93 is a pair of diametrically opposite pilot arms 94. Each pilot arm carries a tooth 36b preferably identical with the tooth 36 and held in position by a clamp 41b preferably identical with clamp 41. A recess is formed in arm 94 having an abutment 96 against which the back of clamp 41b seats and having a bottom surface 97 against which the underside of tooth 36b fits. The teeth 36b shown in FIG. 8 are inclined downwardly and inwardly into as close proximity to the gimlet 92 as is possible so that they cut swaths which intersect the hole formed by the gimlet 92.

In the assembled position of the device, extension 93 fits up through bore 91 and into the lower end of shaft 83. Preferably the shaft 83 is formed with a socket 94 which is complementary to extension 93. A transverse bolt 96 passes through aligned holes in socket 84 and extension 93 and is held in place by nut 97. Thus, bolt 96 secures the pilot to the head and the head to the auger shaft 83. For further facilitation of assembly, the hub 12 and extension 93 may be formed with aligned apertures such as the aperture 98 shown in FIG. 1 and an additional bolt and nut (not shown) passed through such aligned apertures.

What is claimed is:

1. An auger head comprising a hub, means for securing said hub to an anger, at least two arms projecting from said hub and for each said arm an extension arm, said arm and extension arm having cooperating means for sliding said extension arm longitudinally of said arm in telescopic manner while maintaining said arm and extension arm against disassembly, and means for securing said extension arm to said arm in one of a plurality of positions of adjustment to determine the radial projection of said extension arm from said hub, an expansion tooth holder on the top of one said extension arm, at least one expansion tooth in said holder and means mounting said holder on said extension arm to pivot about an axis perpendicular to said arm.

2. An auger head according to claim 1 in which said expansion tooth projects laterally of said head whereby when said head is rotated in one direction said expansion tooth drags against the side of the hole being dug and pivots to a first position extending outwardly beyond the outer end of said extension arm for digging action and when said head is rotated in the opposite direction said expansion tooth drags against the side of the hole being dug and pivots to a second position at a distance from said hub substantially less than said first position.

3. An auger head according to claim 2 which further comprises cooperating means on said extension arm and said expansion holder limiting outward movement of said expansion tooth, one said cooperating means being adjustable to adjust the limit of ourward projection of said expansion tooth when in first position.

4. An auger head comprising a hub, means for securing said hub to an auger, at least two arms projecting from said hub and for each said arm an extension arm, said arm and extension arm having cooperating means for sliding said extension arm longitudinally of said arm in telescopic manner While maintaining said arm and extension arm against disassem bly, and means for securing said extension arm to said arm in one of a plurality of positions of adjustment to determine the radial projection of said extension arm from said hub, a plurality of cutting teeth extending from said extension arm, a clamp for each said tooth and a bolt for each said clamp extending through said clamp, said extension arm and said arm, said clamp clamping said tooth against said extension arm.

5. An auger head according to claim 4 in which said extension is formed with a shallow recess below said tooth and which further comprises a washer compressed in said recess and frictionally restraining withdrawal of said tooth from a position between said clamp and said extension arm.

6. An auger head according to claim 4 in which said tooth is formed with a slot extending from the proximal end' thereof distally, said bolt passing through said slot.

7. An auger head according to claim 4 which further comprises a wedge shaped element between the underside of at least some of said teeth and said extension arm, at last one said lement being disposed at a different angle than a second said element, whereby teeth abutting said elements assume dil'frent angles relative to said extension arm.

8. An auger head according to claim 7 in which said :lements are separable wedge-shaped washers.

9. An auger head according to claim 7 in which said :lements are integral bosses on the surface of said extension arm.

10. An auger head comprising a hub, means for securing said hub to an auger, at least two arms projecting from said hub and for each said arm an extension arm, said irm and extension arm having cooperating means for slid- .ng said extension arm longitudinally of said arm in telescopic manner while maintaining said arm and extension arm against disassembly, and means for securing said ex- ;ension arm to said arm in one of a plurality of positions of adjustment to determine the radial projection of said extension arm from said hub, said arm having a downwardly-forwardly slanted forward face and a non- :ircular cross-section, said extension arm having an underside engaging the forward face of said arm and top and rear lips curled around the bottom and rear edges of said arm.

11. An auger head according to claim 10 in which the forward face of said extension arm is parallel to the forward face of said arm.

12. An auger head comprising a hub, means for se- :uring said hub to an auger, at least two arms projecting from said hub and for each said arm an extension arm, said arm and extension arm having cooperating means for sliding said extension arm longitudinally of said arm in telescopic manner while maintaining said arm and extension arm against disassembly, and means for securing said extension arm to said arm in one of a plurality of positions adjustment to determine the radial projection of said extension arm from said hub, said extension arm being formed with an aperture on its top surface spaced a short distance inward of the outer end of said extension arm, an auger having a helical flight, said flight truncated at its lower end to fit over the top of said extension arm and having a projecting apertured lug, and fastening means through said lug and aperture to secure said flight to said extension arm.

13. An auger head comprising a hub, means for securing said hub to an auger, at least two arms projecting from said hub and for each said arm an extension arm, said arm and extension arm having cooperating means for sliding said extension arm longitudinally of said arm in telescopic manner While maintaining said arm and extension arm against disassembly, and means for securing said extension arm to said arm in one of a plurality of positions of adjustment to determine the radial projection of said extension arm from said hub, a gimletshaped pilot, a pilot head on the upper end of said pilot, cooperating means on said hub and said pilot head to join said auger head and pilot together, projecting arms on said pilot head formed in the pockets, removable teeth in said pockets, and means for detachably holding said teeth in said pockets, said pockets shaped to hold said teeth pointing downward and inward whereby their cutting edges are closely proximate the hole formed by said gimlet.

14. In combination, an auger head and pilot according to claim 13 and an auger, said auger having a hollow shaft and a flight around said shaft, said hub being apertured and aligned with said shaft and comprising one of said cooperating means, the other said cooperating means comprising a noncircular upward extension on said pilot head fitting through said hub and into said shaft and fastening means to secure said shaft and extension together.

References Cited UNITED STATES PATENTS 945,016 1/1910 Caldwell 384 1,052,506 2/1913 Naville 175384 1,993,948 3/1935 Schroeder 175-384 X 2,783,974 3/1957 Veasman 175-384 2,952,085 9/1960 Petersen 175383 2,990,896 7/1961 Kandle 175292 X 3,385,383 5/1968 Sturgeon 175292 DAVID H. BROWN, Primary Examiner US. Cl. X.R 175384, 388 

